Thoughts on Trinitarianism
Given the general track of society, maybe it is suprising this did not occur sooner. In the evengelical church at large there has long been a noticeable lack of teaching of doctrine in general, and the doctrine of the Trinity in particular. Preaching has tended to focus on more practical matters, like becoming a better leader, unlocking our internal potential, or finding our purpose. The church has had little time for such esoteric doctrines like the Trinity that have little impact on how we live our daily lives.
Of course, this is a false assumption. How and what we think about God affects every aspect of our lives, but generally at a level below our purposeful living. John Calvin, after the introductory material, starts his "Institutes of the Christian Religion" with the statement, "Our wisdom, in so far as it ought to be deemed true and solid Wisdom, consists almost entirely of two parts: the knowledge of God and of ourselves." Calvin goes on to argue that the two (knowledge of self and knowledge of God) are so linked as to make it nearly impossible to separate. (It is worth noting that Calvin saw the "Institutes" not primarily as a theological text book, but a handbook for Christian living.)
Therefore, having a correct understanding of who God is will enable us to have a greater understanding of who we are. Whether God exists as one person from eternity that has revealed Himself in different ways or He exists as three persons, co-equal, all fully divine, all truly God has a great impact on the nature of all existence. Also, how we view Him will have an impact on how we live in and percieve the world. If God is a Trinity, then all of existence is relationship. The very nature of being is bound up in personal interaction. Statements such as "It is not good for man to be alone" take on a much clearer significance, since "alone" and "exist" are not compatible terms.
Other considerations include the nature of the atonement, and the distinct roles that each person in the Trinity fulfill in bringing salvation to mankind (see Ephesians 1:1-14 to see how Paul discusses how each member of the Trinity works in our salvation). As churches we do not preach and teach on the Trinity in part because we do not preach and teach the Scriptures. If we did so, we would have to deal with passages like Ephesians 1:1-14 and then discuss the Trinity.
The argument that the Trinity is too difficult a topic is irrelevent. Any topic that truly deals with who God is will be too difficult for us. We are finite creatures trying to comprehend God. We will fall short. But God has revealed Himself to us and we should strive to understand what we can, knowing at the end we will have to declare that the mystery is too deep for us. We can no more understand how God can exists as one God in Three Persons than we can understand how Jesus can be fully human and fully divine. At the end of our theology there will always be (should always be) humility, awe, and a willingness to accept the limits of our knowledge. After all, God has told us that we will never know it all, "The secret things belong to the Lord our God, but the things that are revealed belong to us and to our children forever, that we may do all the words of this law." (Deuteronomy 29:29 ESV).
Let us strive to know God to the full extent He has revealed Himself to us, particularly in the person and work of our Lord Jesus Christ.